122 POL ANN MED. 2020;27(2):122–127 Polish Annals of Medicine Journal homepage: https://www.paom.pl Research paper Demodex spp. (Acari: Demodicidae) infection in healthy young adults in Poland – occurrence and risk factors Ewa Dzika , Katarzyna Kubiak , Joanna Korycińska , Lepczyńska Małgorzata , Hanna Szymańska Department of Medical Biology, School of Public Health, Collegium Medicum, University of Warmia and Mazury in Olsztyn, Poland ARTICLE INFO ABSTRACT Introduction: Demodex mites are associated with various symptoms pertain- Article history ing to facial and eyelid skin in humans. Demodicosis is often reported in elderly Received 4 April 2020 people, above 50 years of age. In young adults, the Demodex spp. infection is less Accepted 29 April 2020 common and is asymptomatic or the symptoms are mild. Available online 11 July 2020 Aim: The aim was to evaluate the occurrence of Demodex spp. in healthy young Keywords adults in Poland and analyze the associations between the presence of mites, par- Poland ticipants gender and skin type, with regards to hygienic practices and symptoms. Students Mites Material and methods: The content of facial sebaceous glands and eyelash Demodex follicles was examined in a group of 94 people, aged 18–32 years. Metric data Healthy young and information about face and eyelid skin symptom occurrence, skin type and hygienic practices were collected by diagnostic survey. Doi https://doi.org/10.29089/2020.20.00109 Results and discussion: Demodex spp. was identified in 21.3% of subjects. In 45% and 30% of carriers Demodex folliculorum and Demodex brevis occurred, User license This work is licensed under a respectively. A mixed infestation in 25% of subjects was detected. Demodex infes- Creative Commons Attribution – tation was slightly higher in people with oily and mixed skin (23.5%), compared NonCommercial – NoDerivatives to those with dry and normal skin (18.6%). No significant influence of shared 4.0 International License. hygienic accessories on the level of Demodex spp. infection were observed. The skin symptoms of the face and eyelids were reported at 75% for subjects positive for Demodex. Conclusions: Demodex mites are often prevalent in healthy young adults in Poland in both the sebaceous glands of the face and hair follicles. While diagnos- ing face and eyelid skin diseases in young people, Demodex spp. infection should be considered. Corresponding author: Katarzyna Kubiak, Department of Medical Biology, School of Public Health, Collegium Medicum, University of Warmia and Mazury in Olsztyn, Żołnierska 14c, 10-561 Olsztyn, Polandtel./fax +4889 524 61 16. E-mail address: [email protected]. 123 POL ANN MED. 2020;27(2):122–127 1. INTRODUCTION ces. The reason for skin symptoms might also be caused by blockage of follicles and sebaceous glands by Demodex mites 16 The hair follicle mites of the Demodecidae family are cos- that leads to epithelial hyperplasia and hyperkeratosis. mopolitan, specialized and obligatory parasites of both Demodex mites might also trigger the mechanisms leading humans and animals.1 Among 140 species described so far, to skin inflammation which are not caused directly by tis- only Demodex folliculorum and Demodex brevis are specific to sue damage. Demodex mites contain lipase, supposed to be humans.2,3 Demodex folliculorum usually inhabits facial hair able to aggravate skin conditions by transforming sebum follicles, but may also colonize the sebaceous glands (Zeiss’ into certain components, which are clearly cytotoxic, and 18,19,20 glands) and hair follicles of eyelashes. Demodex brevis lives irritants. It has been established that Demodex mites deep in the sebaceous glands of facial skin (around the nose, can also be a vector of the pathogens Bacillus oleronius and eyes, forehead, chin, and nasolabial fold) or the Meibomian Staphylococcus epidermidis, which may play a prominent role 9,21 gland of the eyelids.4,5 Both species may also occur in the in the pathogenesis of demodicosis. hair follicles or skin sebaceous glands of other body parts. The prevalence ratio of D. brevis and D. folliculorum in males and females is 1 : 4 and 1 : 10, respectively.6 Any particular 2. AIM human may be a carrier of a Demodex colony consisting from 1000 to 2000 specimens. The epidemiological study of Demodex spp. prevalence in The life cycle of Demodex lasts from 14 to 18 days and humans shown having a high dependence on the patient’s requires only one host.7,8 These parasites avoid the sunlight age. Most often demodicosis in elderly people over 50 years 22,23 in all of the developmental stages. Their copulation occurs old is reported. It has been suggested that the percent during the night, near the entry to the hair follicle and the of infestation in young people, about 25 years old, is low- 24 subsequently fertilized female migrates to the sebaceous er. The aim of this study is to determine the prevalence of gland where she lays less than 20 eggs.7,9 After copulation, Demodex mites in the young adult population living in the the male dies.10 The larvae hatch after 60 h, molt twice and North–East of Poland and also the association of the species transform into a deutonymph – the infective stage for hu- occurrence with the facial area, gender, skin type, hygienic mans.9 The deutonymphs evolve to the adult form after the habits and symptoms. next molting.10,11 All of the developmental stages of Demodex spp. feed on epithelial cells, the content of sebaceous glands (sebum), lymph and plasma.7 3. MATERIAL AND METHODS Humans may contract the parasite by direct contact 3.1. Study population with a carrier of Demodex spp. as well as indirectly by us- ing common towels, sheets, cosmetics or toiletries.8,10 It has A total of 94 young healthy volunteers (students of the Uni- also been documented that infants may become infected by versity of Warmia and Mazury in Olsztyn) were examined. contact with colonized mothers skin.12,13 Therefore, Demo- The study group consist of 73% females (n = 69) and 27% dex mites have a cosmopolitan distribution and are found males (n = 25), aged 18–32 (average 20.2) years old. The in about 10% of biopsy specimens of healthy human skin, content of facial sebaceous glands (forehead, cheeks, nose, where they are present in about 12% of all follicles. Various chin) and lashes from both eyes were collected from 81 par- studies have shown normal rates of colonization to be 20% ticipants. From the 13 volunteers, only lashes with a root to 80%.12,13 The prevalence of both Demodex species increases of hair were collected to identify the Demodex occurrence. with the host age and in adults reaches even 100% with a Metric data (age and gender), information about skin symp- density of more than 5 mites per 1 cm2 of normal skin.14,15 toms of the face and eyelids, skin type and hygienic habits from examined students were collected to determine the Usually the Demodex infection in humans occurs asymp- risk factors of Demodex spp. infection and associated pos- tomatically. Primarily Demodex mites have been treated as sible symptoms (skin symptoms as itching and irritation of a commensal fauna on mammalian skin.14 The host’s im- the skin, eczema, acne and ocular symptoms: inflammation mune status and changes in the skin microenvironment can of the eyelids, itching, madarosis). Data were collected by facilitate a rapid propagation and consequently change it self-design diagnostic survey questionnaire. into a pathogen.5,16 An increasing number of Demodex mites in human skin is associated with the pathogenesis of some 3.2. Detection of Demodex mites dermatoses including demodicosis, rosacea or blepharitis as The Demodex mites were detected in the content of the fore- well as with immunosuppression caused by the natural ag- head, cheeks, nose and chin sebaceous glands (black head) as ing processes and the occurrence of other diseases.5,16,17 The well as in the roots of the upper lashes of both eyes. Samples skin symptoms caused by Demodex spp. show up because were obtained from the volunteers by squeezing method and mites are moving from hair follicles and sebaceous glands to by epilation, early in the morning. The sterile gauze swabs, surrounding tissues. The Demodex antigens trigger the host epilating forceps and microscopic slides were used for asep- immune reaction, which is the direct cause of rosacea symp- tic material collection. The material was set separately into toms. Similar triggers have been reported from parasite fe- a Hoyer liquid drop25 and observed under light microscope 124 POL ANN MED. 2020;27(2):122–127 Table 1. The infection by Demodex mites and species distribution in according to gender. Demodex P Demodex species / Demodex positive (%) P Gender positive/tested OR(95%CI) value* value* n(%) D. brevis D. folliculorum D. brevis / D. folliculorum Female 17/69 (24.6) 4/17 (23.5) 8/17(47.1) 5/17 (29.4) 0.42 0.277 Male 3/25 (12.0) 0.186 2/3 (66.7) 1/3 (33.3) 0/3 (0.0) (0.11–1.57) Total 20/94 (21.3) 6/20 (30.0) 9/20 (45.0) 5/20 (25.0) 0.522 Comments: *χ2 test; OR – odds ratio; CI – conficence interval. by 100× and 400× magnification. Each sample containing Based on the morphological features, D. folliculorum was a mite, from any developmental stage (adult form, nymph, in 45.0% (n = 9) of infected volunteers (Figure 1). Demodex egg), was considered as a positive result. The Demodex species brevis occurred in 30.0% (n = 6) of carriers. Mixed infesta- were identified according to its morphological features (spec- tion was found in 25.0% (n = 5) of persons.